This is a remix from PADDYY_3D. you will need to buy his file to complete the print. i am sharing only the parts i modified to make the glowing flames.
https://youtu.be/-dvdUh1GWZc

files can be bought here:
https://cults3d.com/en/3d-model/art/balrog-stylized-3d-print-model-3d-print-model
https://www.cgtrader.com/3d-print-models/art/sculptures/balrog-stylized-3d-print-model

instructions on how to make them are here:
https://www.instructables.com/Balrog-Glowing-Flames/